s1_generate_a_series_of_files(){
	for i in {1..100}; do
		echo -n "$i" > "/tmp/new_file$i"
	done
}
s2_list_4_files_in_long_format_about_account_and_group(){
	ls -lh /etc/passwd /etc/group /etc/shadow /etc/gshadow | LC_ALL=C sort
}
s3_find_items_related_to_given_username(){
	grep -h $1 /etc/{passwd,shadow} | sort -d 
}
s4_find_items_related_to_given_group_name(){
	{ grep -h "^$1:" /etc/group /etc/gshadow 2>/dev/null || true;} | sort
}
s5_create_groups_for_given_group_names(){
	sudo groupadd rnd
	sudo groupadd itoperation
}
s6_create_users_and_set_their_group_as_required(){
	sudo useradd -G rnd adam
	sudo useradd -G rnd bob
	sudo useradd -G rnd edward
	sudo useradd -G itoperation calvin
	sudo useradd -G itoperation david
}
s7_change_users_shell(){
	sudo usermod -s /usr/bin/sh adam
	sudo usermod -s /usr/bin/sh edward
}
s8_set_password_change_policy(){
	for user in adam bob calvin david edward; do
		 chage -m 10 -M 60 -W 10 "$user"
	done
}
s9_set_password_for_five_users(){
	if [ $# -ne 5 ]; then
		echo "错误：需要5个密码参数"
		return 1
	fi
	users=("adam" "bob" "calvin" "david" "edward")
	password_data=""
	for i in {0..4}; do
		password_data+="${users[$i]}:${1}"$'\n'
		shift
	done
	echo "$password_data" | sudo chpasswd
}
s10_lock_bobs_password(){
	sudo passwd -l bob
}
s11_include_adam_into_wheel_group(){
	sudo usermod -aG wheel adam
}
s12_change_files_permission(){
	for i in {1..100}; do
		if((i%1==0)); then
			chmod 640 "/tmp/new_file$i"
		fi
	done
}
